In many configurations of air conditioning units, the air flow rates into the side outlets of the instrument panel are defined for the window ventilation mode, the floor/window intermediate mode and the floor ventilation mode. This air is used to prevent the side windows from fogging or icing up and to deliver some warm air between the cold window and the passengers in order to enhance the temperature comfort. In most cases, the air conditioning unit is equipped with one or several damper doors at the openings for the side regions and the central region of the instrument panel. Thereby, the flow path to the central region of the instrument panel must be configured closable by use of the appropriate damper door while the flow path to the side openings of the instrument panel keeps opened. Frequently, the outlet of air into the side regions of the instrument panel is ensured by that at the instrument panel side outlet damper doors, there are holes and/or regions that cannot be closed at all. It is disadvantageous of these designs that, with the exception that the hole sizes at the outlet damper doors are dimensionable, they do not allow the air flow rate into the side regions of the instrument panel to be controlled. The air flow rate can only be tuned for one ventilation mode, for example, the floor mode. For other modes such as the window mode or the floor/window intermediate mode, there is no possibility at all to adapt the air flow rate exiting through the side openings of the instrument panel.
Devices for control of several different air flow rates are disclosed in the following documents.
In DE 100 48 529 A1, the different air flow rates are set by means of at least two damper doors mounted on a shaft. By rotating only one shaft, the damper doors mounted on said shaft can be moved. The single damper doors include means for adjustable, opposite-sense setting of several air flow rates to different air guiding channels. As an advantageous embodiment, it is recommended that the at least two damper doors mounted on the shaft should be oriented at an angle of 60° to each other. In this way, by simple means, the possibility is raised to provide several air guiding channels with the desired air flow rates using one single mechanical component. A disadvantage of this embodiment is that no independent control of the air flow rates through one or several damper doors is possible when one of these damper doors is closed.
In DE 101 35 330 A1, a drive mechanism for damper doors is described that serve to control the flow through air guiding channels of a vehicle heating or air conditioning unit. Several damper doors, preferably three, are operated by means of a common drive. One of the damper doors is only moved over part of the opening or closing motion of the other damper doors but held in a closing position for the remaining part of the pivoting motion. A common drive is provided with at least one gear wheel which engages with segment gears of both damper doors, whereby a segment gear the next to last tooth of which is omitted is assigned to one of the damper doors so that the toothing can get out of gear. At the same time, a lever connected with the segment gear engages with the gate ensuring continued holding of the damper door in the closing position. An offset pair of teeth located outside the toothing plane ensures defined re-engagement of the separated gears. The advantage of such a design is that it enables to move different damper doors on one shaft and hold, however some of them in the closing position independent of the other ones. Disadvantageous are the material and cost efforts for such an expensive realization.
It is the objective of the present invention to establish an instrument panel damper door device in the casing of a vehicle heating or air conditioning unit while maintaining the advantages of the art, such that separation and independent control of the air flow rates is achieved with means that are plain in design.